Method and apparatus for cooling buffs and polishing wheels



NOV. 10, 1953 1 R DAWES 2,658,316

METHOD AND APPARATUS FOR COOLING BUFFS AND POLISHING WHEELS Filed Sept. 8, 1950 IN VEN TOR.

Patented Nov. 10, 1953 UNITED fsTArl-:s PATENT "o1-rica METHOD D FAPPARATUS :FOR COOLING TBUFFS AND POLISH'ING WHEELS Joseph R. Davies, "Chicago, Ill. l fAppllcationgSepfeniber 8, 1950,SerialiNo..183}724 "5Clms. (Cl'51-f2'67) This` invention relates to a method :andf apparatuslfor cooling. grinding'- and polishing surfaces, and :particularly -to cooling 'the -cores `or* central .Jportions of buffs,` polishing -wheels-fand belts.

-The -qualityand speedfongrinding, buing and polishing is very dependentupon the -heat of l operation of the buff or Wheel. The heat ris gen- -erated at theperipheryf and a: substantial portion is dissipatedin the air. However, there is a substantial andsteady-ow'oi heat -from the peripheryV inwardly toward the: hub and as this heat in-the'hub cannot be dissipated quickly, it-stead- `:ily increases, anddfthe grindingorbufng operationisnot-at least temporarily terminated, -the buff may burn, lbut -even before burning, the cloth may lose its tensile vlstrength due to ythe heat, and deteriorate. VAInsthe case offgrinding or polishing wheels Whereinnthe` cloth layers at -the lsurface -are -cemented vtogether with glue which holds the grinding'powder, Athe cloth-ex pands underthe-heatandAchunks ofA cloth, grinding -compound and fabric may cr-aclrk off the periphery, necessitating complete rer'iishingl of the wheel.v Indeed, where polishing wheels-are being -pushed vto their limit, in ,getting out rushl workl the heat has -eausedv the polishing-wheel to explode right on the job.

Thisis an oldproblem and has'been partially solved by designing -burls and components of polishing wheels Withradial-.passagewaysvfor air,

from the hub toward theperiphery. ffIhese passagewaysinthe case of buffs vpass through the periphery andfprovidefa.certain amount of cool- Aing. fn'the case-of the polishing wheels, the

.passageways are usually parallel with the v.axis around Whichthe Wheel rotates and there is lit-v tleor no passagel of airthrough.the.periphery which isf quite harddue to the/presence of .glue Aand grinding powder. -Despitethese lairpassage- Ways, bun? and polishing wheel temperatures buildy up soV that the. operation'y must lbe Y stopped if the maximum life of the is 4to'be attained.

4It Voccurred to ther applicant vthat `the method of dissipating heatin buffs and polishing Wheels in the past was inadequate vbecause theydepended -upon -the circulationof air which has avery limited capacity to absorbheat, as does anygas. In order-to absorb an appreciableamountof heat fcollectedinthefbody of a buff orpolishng lWheel an enormous amount ofair or any gasA must.-be

fstate. #Bearing in mind that it requires 536times .as I manycalories to vaporize a quantity .of ywater at1212 as isfrequiredtoraise its'temperatureby one degreefcentigrade, it ,is self-evident that@l great deal :of heat .can =be removed whenever vapcrization-takesfplace.

Applicant proceeded .to xinvestigate theburning temperatures of materials -used in ibuffs .and polishing Wheels. The -burning temperature of cotton was not lower than 220 Fahrenheit, that is, eight degrees above fthe #boiling point of awater. The vast maj ority. of buis l,are made-.of cotton material. .There are-.piece 'buffs :made of r4textile remnants, aand these remnants l may include small amounts ofI silkflinenvand woo1,.but these fibers arebOmparativelyrare. .Therelare also .some buis made'ofesisalrand jute. Here again, the volume is small compared to vvcotton. In the ease of sisal andzjuterhoweventhe;burning ori-lash point is highenthanpotton. .Applicant thereupon .realized that \he :could lkeep buffs from Yburning by keeping the l .core wet.

However, this does not .solve very. muchin-the oase of Veither buffs or grinding'wheels becauseif a whirling grinding ewheel `Ywill f .centrifugally ,ex-

pel air, afortiori itwill-,expel'water fand.this-wa ter Will` adversely affect 1 the .grinding f .compound .on either a bufforapolishing wheel.

`The generalv object .of e this e invention is nto-.cool buffs, polishing .wheels and polishing belts .by

`evaporating smallfparticlesof a liquidfsuch--as of lair due to .centrifugal action, -and a...spe

cic object ofthis .inventionis to introducesmall Water particles 'to this :air vwhich will .deposit themselves on inrierlsurfaces-A of .the vlouiiing `section and -will 1 thenz-be.' evaporated rWhen-.the ;bu1 temperature rises` toa selectedwpont. n

A second specitlcaobject of` this:v inventionisto yintroduce air under .pressure .near the Vhubof thesev bung sections so fas-1 to increasesubstan- -tially the circulation lof vaporizable lWater particles through the buff.

The invention mayv /alsol be adapted .'to- `polishing wheels, grinding wheels .and abrasive belts.

f As the vperipheral surfaces of. theseabrasive media are .almost impervious tothe,passagev of air,l it 4is a specific object yof gi-nventionto A.prnvide means for introducing fine particles of water into air passageways near the polishing wheel hubs and through which there is a flow of air.

Another object of this invention is to control the amount of cooling liquid particles that are introduced into the abrasive media so that the minimum temperature necessary to flow the metal of the Work at the point of contact can be maintained while nevertheless preventing excessive temperatures back toward the center of the wheel. By eliminating excessive temperatures, not only is the cloth of which the abrasive media is formed preserved from deterioration, but particularly in the tightly packed polishing and grinding wheels, bad effects due to expansion of the material are avoided.

These and such other objects as may hereinafter appear are attained in the description of the method and the embodiment of the invention Fig. 1 is a view in vertical side section of a -ventilated bufling wheel on a shaft with applicants apparatus mounted on one side thereof;

Fig. 2 is a vertical side section of a polishing wheel having a modified form of applicants apparatus for introducing water particles mounted on either side thereof;

Fig. 3 is a view taken on the line 3 3 of Fig. 1; and

Fig. 4 is a schematic illustration of a simplied apparatus to practice applicants method.

Continuing to refer to the drawings, in Fig. l, the numeral I identifies a shaft upon which has mounted four buffs I2, I4, I6 and I8, which are held in spaced relationship by shoulders 20, and constitutes a ventilated buing wheel. The particular type of buff is not important. The buffs illustrated are annuluses, each mounted on a core made of wood or steel. A plurality of solid buffs, that is, buffs in which the core portion is formed integrally with the bui itself, as for example, the buff sections 22 shown in Fig. 2, may be used. 'I'he important thing is that the buff sections be spaced from each other so as to provide air passageways 24 radially directed.

Transversely through these buff sections or cores of buff sections are passageways 26 which intercept the radial passageways 24 so that there may be a flow of air from the former, through the latter and to the working periphery of the buff. The buff sections are held in assembled relationship by a solid plate 30 and a plate 32 having holes 34 alignable with passageways 26.

The structure now to be described is more schematic than realistic or commercial. It illustrates experimental apparatus. Mounted on the shaft I0, adjacent the plate 32 is a collar 36 upon which is mounted a bearing assembly 38 which in turn carries a wheel 40. This Wheel 40 consists of a hub 42, spokes 44 and a tubular rim 52 from which projects inwardly nozzles 54.

A bell 56 is mounted outside the collar 36 on the shaft I0 and is held thereon by nut 31. The bells outer edge 51 is positioned close to the circumferential edge of the plate 32. A conduit 68 taps the tubular rim 52 and passes through an opening 60 in the bell 56 to a tank of water under pressure 64. Mounted externally of the bell 56 and concentrically of the shaft l0 is a circular tube 66 lhaving holes 68 through its inside wall in alignment with openings 10 in the bell. These The operation of the apparatus is as follows. As the bufng operation is commenced and the buff rotates, comparatively little air is thrown radially because there are no vanes in the passageways 24 to cause circulation. 'I'he wheel 4l and the bell 56 assembly remains motionless. A valve 18 in the water line is opened and a spray is produced in the annular area 80. This spray is not vaporized water but fine particles of water which are momentarily suspended in the air. concurrently, the valve 14 is opened and compressed air is introduced through the plurality of openings 10 which in turn blows the mist at into the passageways 26. Since the passageways 24 are the only means of escape for the air, the air is forced outwardly.

Many of the water particles deposit themselves on the surfaces of the buil. between the point 82 and the periphery. As the temperature of the buiT rises, the deposited Water particles will vaporize and in so doing, will remove heat from the buff. The air flowing in the passageways 24 will carry the vapor and heat out of the buff section.

It is seen that applicants method consists in the step of adding minute water particles to exposed surfaces centrally of a buff and of then providing a carrier, that is, the air, to remove the vapor evolved from these water particles after their temperature has exceeded a certain point, Applicant regulates the flow of water into the buff core so as not to get the cores too wet. The quantity of water introduced will vary depending upon the kind of bufling work that is being done. If the work is such that high temperatures are caused in the buff, additional water will be carried into the buff.

Applicant has experimented with other apparatus to accomplish this same result. Thus, in Fig. l, the tank 64 is shown as containing water only and the mist eifect is obtained by the nozzles 54. Applicant has been experimenting with a device for producing a mixture of air and water in a tank such as 64 and forcing this mixture of water and air into the areas 80. Under these circumstances, he does not rely upon nozzles to attain the desired diffusion of water particles.

He has also considered the construction illustrated in Fig. 4. Here a buff is schematically shown with transverse passageways 92 and radial passageways 54. A compressed air tank 96 is connected through a hose 98 to an atomizing head |00. To the bottom of this head is fastened a jar filled with water |02. The nozzle |04 is aligned with the passageways 92 which due to the revolution of the buff will successively pass the nozzle |04. This arrangement is considerably simpler than the structure shown in Fig. 1 but is not quite as effective because since the air is blown into only one of the passageways 92 at a time, and since these passageways are connected to each other interiorally of the buff core, the air currents are set up in conflicting directions instead of entirely radially. This is to be contrasted with the bell arrangement shown in Fig. l where once the air enters the buff, it enters through all of the passageways 26 at the same pressure and consequently the water particles are carried to the various parts of the buil? fairly uniformly.

Thus far applicant has been describing the cooling of a buff, by which he means a disk structure whose peripheral surface is formed of comparatively loose threads uncompacted by gelatine, glue and grinding compound. Grinding compound may be applied to the surface of these buifs, but the surface is nevertheless flexible and loose. The invention is also beneficial for use on a polishing wheel. A polishing wheel might be formed of the very same buff sections that are shown in Fig. 1, but generally is formed of solid buif sections as illustrated in Fig. 2. These sections are not spaced from each other and hence no substantial quantity of air can move radially from the hub to the periphery. Also, the polishing wheel periphery is hard as it carries a mixture of grinding compound and glue. Common practice is to punch holes through the assembled wheel parallel to the axis, as for example, |06 in Fig. 2. In this figure, the water atomizing assembly is identical with that shown in Fig. 1. However, the compressed air connection is omitted. This ycompressed air connection could be mounted on the assembly in Fig. 2 as in Fig. 1, and the water particles driven into the passage- Ways |06 as heretofore described. However, in this assembly, applicant has mounted on the right-hand side of the shaft a collar ||0 which carries a bell ||2 held on a shaft by a nut ||4. An opening ||6 in the bell Wall is connected to a suction pump |20 by a conduit ||8. The suction pump creates a partial vacuum inside the bell and while there is substantial leakage at the points |20 and |22, the pressure at the point |24 is substantially below atmospheric pressure and there is a flow of air through the passageways |06. This flow of air picks up the small water particles and more slowly carries them into the passageways |06 and |00 where they are deposited on the walls. As the temperature of the polishing wheel rises near its hub, these water particles vaporize and take up heat and are withdrawn through the bell on out through the suction pump.

Applicants method of cooling bufling and polishing wheels can also be applied to grinding wheels and belts. Essentially, the idea is todeposit particles of water on some surface of the bufiing media which acquires heat from the work surface but which itself is not part of that surface, and then when these water particles vaporize and take heat out of the buff material, to carry off the vapor and to re-deposit more water particles. In certain kinds of operations, a belt is passed over a wheel between the wheel and the article to be buffed and thence over another wheel which is the driving Wheel. The belt passes through air and is cooled. Applicants idea would be to spray the back of the belt with Water particles which in turn will vaporize and cool the belt.

In order to simplify the language of the claims, the words buffs and "bufiing include not only what are technically known as buffs or "buifing in the trade, but also polishing and grinding wheels and belts made of the materials referred to in thisy specification.

Having thus described applicants invention, what he claims is:

1. A bufng assembly comprising a shaft, flexible bufiing units rotatably mounted on said shaft, a side opening through the walls of the buffs parallel and adjacent to the shaft, means spacing the buffs from each other near the hub so as to form air passageways connecting the firstmentioned opening to the inner side surfaces of the buffs, the flexibility of the bufiing units being such that during operation the peripheral surface is substantially continuous so that the air passageways from the hub to the periphery are interrupted by the flexible material of the bufling unit, means for forcing an air stream under pres.-

sure into said opening and against the inner side walls of the buffs, and means for introducing particles of water into said air stream at a point near said opening.

2. A buing assembly comprising a shaft, exible bufiing units rotatably mounted on said shaft, a side opening through the walls of the buffs parallel and adjacent to the shaft, means spacing the buffs from each other near the hub so as to form air passageways connecting the firstmentioned opening to the inner side surfaces of the buffs, the flexibility of the bufiing units being such that during operation the peripheral surface is substantially continuous so that the air passageways from the hub to the periphery are interrupted by the iiexible material of the bufling unit, means for forcing an air stream under pressure into said opening and against the inner side walls of the buffs, and a liquid atomizing means mounted adjacent the entrance to said side opening in the Walls of the buff and in the path of the air stream.

3. The method of cooling circular bufiing elements composed of layers of inflammable, fieXible disks of fabric which comprises the steps of impinging vaporizable liquid particles on the side walls of said disks in amounts sufficiently small so that the peripheral working surface does not become wet, and of carrying off the vapor resulting from the particles contacting the hot surface in a flow of radially directed air.

4. In the method of cooling circular buing elements composed of layers of inflammable, fiexible disks of fabric wherein air is introduced adjacent the hub for circulation radially along the side surfaces of said disks, the step of adding liquid particles to the air prior to its passage radially along the surfaces of the disks in such small quantities that the particles, upon engagement with the side surfaces of the disks, will vaporize and not wet the peripheral working surface of the buff.

5. The method of cooling rotating, circular bufiing elements composed of layers of infiammable, flexible disks of fabric which comprises the steps of introducing air between the surface of said disks adjacent the hub and of suspending finely divided particles of water in said air immediately prior to its introduction to the buing element and in such small quantities that the water will vaporize on contact with the disks and not wet the peripheral work surface.

JOSEPH R. DAVIES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 376,854 Cavert Jan. 24, 1888 500,561 Carpenter et al July 4, 1893 524,572 Beckert Aug. 14, 1894 796,466 Stolzenberg Aug. 8, 1905 1,491,515 Chase Apr. 22, 1924 2,080,206 Holmboe May 11, 1937 2,087,012 Zimmerman July 13, 1937 2,182,952 Todd et a1. Dec. 12, 1939 2,378,070 Eastwood June 12, 1945 2,380,332 Scheer July 10, 1945 2,479,941 Kummer Aug. 23, 1949 2,560,944 Garrison July 17, 1951 FOREIGN PATENTS Number Country Date 210,580 Great Britain Feb. 7, 1924 511,547 Germany June 30, 1929 

